Can a Radeon HD 6570 run on a 300w PSU or should I upgrade to a 400w PSU

yes you can run the radeon 6570 on a 300w power supply but it all depends not only on how much draw your cpu has but also your disk drives and fans example the core i3 has a power draw of 64w at max load so with the i3 you would be able to use your power supply or you can check to make sure on extreme power source calculator where itll tell you the estimated amout your total system will run at with that card in there with your components i hope this helps